A wireless microphone has various functions, for example, a function for controlling an output level of a radio wave and a display function. An operation portion for controlling these functions is provided in the wireless microphone. A user of the wireless microphone operates the operation portion to thereby control the functions of the wireless microphone.
For example, in a case where a play is performed on a stage and a performer is carrying and using the wireless microphone, the performer has difficulty in operating the operation portion of the wireless microphone and may in many cases erroneously operate the operation portion.